外研版（2019） 选择性必修 第二册 Unit 6 Survival Using language课件（共18张）

(共18张PPT)
Unit 4
Breaking boundaries
it as an empty subject
1.To understand the general knowledge of it as an empty subject.
2. To be able to use it as an empty subject in proper situations.
Learning aims
观察句子
1．But it is vital not to take any chances.
2．It is important to remember that Ebola doesn't respect national boundaries.
3．It is so inspiring to have colleagues like Wilton...
4．It is no use crying over spilt milk.
5．It is no good sighing about your failure; you'd better start again.
6．It makes me angry that he doesn't study hard.
7．It is not clear whether they consider this opinion or not.
Leading-in
1．句1、2、3中的it作形式主语，真正的主语是后面的_____________。
2．句4、5中的it代替的真正的主语是________________。
3．句6、7中的it代替的真正主语是由____________或____________引导的从句。
Leading-in
to do不定式
V-ing短语
whether
that
当主语部分相对于谓语部分而言太长时，常把主语部分移到句尾，在主语的位置放上it。it 没有具体的意义，仅用于使句子显得平稳，不头重脚轻。it 作形式主语时常代替三种语法结构： 不定式(短语)、v. ing(短语)和从句。
一、it代替不定式(短语)作形式主语
1．It＋be＋名词/名词词组＋to do sth.，这类名词有a habit、a pleasure、a fact 等。
◆It is not a good habit to stay up too late.
睡得太迟不是个好习惯。
2．It＋be＋形容词＋(for sb.)＋to do sth., 这类形容词用来描述不定式行为本身的性质,有necessary、wrong、right、important、difficult、easy等。
◆It is necessary for you to be fully aware of your own shortcomings.
充分认识自己的缺点是很必要的。
3．It＋be＋形容词＋of sb.＋ to do sth.，这类形容词用来描述不定式行为者的性格、品行等时，不定式前常可加一个由of引起的短语。这类句型所涉及的常用形容词有foolish、kind、good、polite、selfish等。
◆It was foolish of you to behave like that.
你那种表现真是太蠢了。
4．It＋takes＋sb.＋时间或金钱＋to do sth.，这是一个表示某人花了多少时间或金钱做某事的句型。其中it是形式主语，代替后面的不定式，句中的sb.也可省略。
◆It took thousands of people many years to build the Great Wall.
成千上万的人花了很多年才建成了长城。
二、it代替v. ing(短语)作形式主语
It＋be＋名词/名词词组＋ doing sth.，这类名词有(no) good、(no) use、(no) time、a waste of time、fun等。
◆The doctor told us that it is no good eating too much meat.
医生告诉我们吃太多的肉没有好处。
【温馨提示】
it作形式主语代替v. ing(短语)时，往往限于以下句型中：It is no good/no use/fun/a waste of time...中，如不是上述句型，在将v. ing(短语)移到句尾用it作形式主语时，v. ing(短语)要改为不定式。
【即学即练】单句语法填空
(1)It is necessary for high school students (learn) another foreign language.
(2)As far as I'm concerned, it's no use (argue) with him, he won't change his mind.
(3)It is essential you to accomplish the papers before Sunday.
(4)It's clever you to work out the maths problem.
of
to learn
for
arguing
三、it代替从句作形式主语
用it 作形式主语的结构主要用于下列句型：
1．It＋be＋名词＋从句，这类名词有a fact、a surprise、an honor、a pity、a wonder、common knowledge等。
◆It is common knowledge that the full moon brings fair weather.
皓月兆天晴，这是常识。
◆It is a surprise that you gave such an answer to the question.
你对这个问题作了这样的回答，真令人吃惊。
2．It＋be＋形容词＋从句，这类形容词有natural、true、strange、necessary、important、obvious、certain、wonderful、funny、possible、likely、probable等。
◆It is certain that free medical care will be given to most people in our city.
我们城市的大多数人将享受免费医疗，这是肯定的。
◆It is probable that he has known everything.
很可能他已经知道了一切。
3．It＋动词＋从句，这类动词有seem、happen、appear、look、matter、make、strike、occur(突然想起)等。
◆It appeared that he had a taste for music. 看来他对音乐有一定的鉴赏力。
◆It made us very happy that she was saved. 她能化险为夷令我们大家非常高兴。
【温馨提示】
在下列句式中，that从句要用虚拟语气：
It is desired/suggested/settled/requested/required/demanded/ordered/proposed/recommended
...that ...
◆Is it settled that he (should) resign his office
他辞职已成定局了吗？
4．It＋be＋分词＋从句，这类分词有 said、reported、believed、known、decided、proved、thought、expected、announced、arranged、amusing、puzzling、striking等。
◆It is said that Li Hao has been to Europe.
据说李昊去过欧洲。
◆It was amusing that a rabbit ran out of the empty box on the desk.
桌上的空盒子里竟然跑出来一只兔子，太有趣了。
【即学即练】完成句子
(1)难怪你累了呢，你一直走了好几个小时。
you're tired, you've been walking for hours.
(2)真奇怪，他没说一声就走了。
he left without telling us.
(3)有人请他在聚会上表演一个节目。
It is requested that he at the party.
(4)我忽然想起我知道怎样解决那个问题。
I knew how to solve that problem.
It is a wonder that
It is strange that
(should) give a performance
It suddenly occurred to me that
Summary
Ⅰ单句语法填空
1．It is required that you (tell) other people the exciting news.
2．It's standard practice for a company like this one (employ) a security officer.
3．It's a waste of time (reason) with him.
4．It was foolish you to leave school at such a young age.
5．It was pretty hard him to bring up the child on his own.
6． happened that the tickets were sold out.
7．It suddenly occurred to him he had left his keys in the office.
(should) tell
to employ
reasoning
of
for
It
that
课时重点回顾
Ⅱ 完成句子
1．吉姆是否适合参加决赛还有待观察。
whether Jim will be fit enough to play in the finals.
2．在清晨游泳很愉快。
in the early morning.
3．秋天树叶从树上落下是常见的。
in the fall.
4．据报道，今晚很可能有飓风。
a hurricane is likely to come this evening.
It remains to be seen
It is fun going for a swim
It's common for leaves to fall from the trees
It is reported that
The greatest test of courage on earth is to bear defeat without losing heart.
世界上对勇气最大的考验是忍受失败而不丧失信心。